1. Field of the Invention
The present invention relates to a manipulator for performing a bending operation of a bending portion, etc.
2. Description of the Related Art
Generally, various kinds of electric instruments using motors as driving means have been widely used. With respect to an endoscope, for instance, as a medical instrument, in addition to an endoscope of a manual operation system in which a bending section provided in an insertion portion to be inserted into a body cavity is manually driven, an endoscope of an electric driving system in which a motor is used as driving means for improving operability has been brought into practical use.
In a case of driving a load by a motor, a sensor for detecting a state of the load is usually used as well as detecting means for detecting an operation state of the motor. For example, in a case of an endoscope, if a sensor for detecting a tensile force acting on the bending portion to drive the bending portion is provided, the insertion portion is made thick or a necessity arises, for example, to make a structure of the sensor have durability with respect to cleaning and disinfecting, which increases cost.
Therefore, technique of a disturbance observer that calculates a disturbance exerted on an output shaft of a motor (a component excluding a driving force generated by the motor itself) from a rotational velocity of the output shaft, etc. by operation processing using software is described in Japanese Patent Laid-Open Publication No. 2007-185355.
As described, by adopting a method of the disturbance observer, a load value of a motor can be calculated as a disturbance estimated value without using a sensor, to eliminate cost increase, etc.
Note that in driving a load side such as bending portion by the motor, a reduction gear unit is used for sufficiently driving the load.